As you may or may not know by now, T-Mobile has gone ahead and released BlackBerry 10.2.1 today. But to be more specific, it's actually OS 10.2.1.2228. That's a higher OS release than some of the other carriers that have already released 10.2.1 and while that might not be a big deal for most folks, if you're fully into running the latest and greatest OS on your device you can now download the autoloaders to facilitate in getting your device updated to OS 10.2.1.2228.
Aside from a few updated system files, it's hard to say what improvements this OS may have over other releases at this point but as people load it up and use it, we'll certainly end up knowing more. You can head on into the CrackBerry Forums to find the autoloader download links, as well discuss what changes you might be seeing after you have it loaded.
Keep in mind, autoloaders wipe your device clean so if you're not wanting to do that then you'll have to look at updating through Sachesi. Finally, if NONE of this makes any sense to you, then it may be best to just stick with the OS you have or ask in the forums for further help on getting it all loaded up. Shout out to Thurask and theonecid for posting them up.